AUSTIN — There’s a famous moment in the movie The Candidate where the campaign manager tells an erstwhile political maverick played by Robert Redford he can say whatever he wants.

Why, the Redford character wonders. Because, the campaign manager scribbles on the inside of a matchbook, “You lose.”

So it is that John McCain, trailing in the polls and facing a growing political tide, is free to recalculate his flailing campaign however he wants, beginning at Wednesday’s final presidential debate. He has everything to win, nothing to lose.

The McCain camp has taken various tacks along the way: the resurgent fighter, the patriot, the seasoned veteran, protector of the homeland, action hero on the economy.

He virtually ignored Barack Obama in the first debate, seemed to coast through the second one and, in recent days, recoiled against the ugly resentments that some of the faithful expressed at campaign rallies.

Going into tonight’s debate at Hofstra University in New York, Mr. McCain faces perhaps his last, best opportunity to change the course of a campaign that’s not going his way. Here’s what he needs to do:

1. Start with a clear message on the economy: I’m for you. The Arizona senator should emphasize he is on the side of homeowners, people worried about their jobs, families anxious about paying the bills.

He needs to serve notice clearly he’s no friend of Wall Street by pledging to throw the crooks in jail. The meticulous details of a bailout plan aren’t as important as creating confidence in voters that he will fight for them and, as important, that he is the only candidate with the experience and fortitude to see the fight through.

2. Throw the Bush administration under the bus. The McCain brand is as a maverick not comfortable with the establishment of either side, Republican or Democrat.

Mr. McCain should remind voters that he denounced the administration’s early failures conducting the war in Iraq. And as for the success of the surge, emphasize what that means: The troops are coming home. Americans are pleased that things are going better in Iraq, but what they want to hear unequivocally that the next president will end the war President Bush started.

3. Foster doubts about Mr. Obama. Elections are about choices. Americans are anxious about their savings and their mortgages, and want in their next president someone cool and competent at the controls. Mr. McCain can never beat Mr. Obama at cool, but his task is to reassure voters that he’d be more competent.

As for Mr. Obama’s associations with “domestic terrorist” Bill Ayers or former pastor Jeremiah Wright, answer questions if asked but allow talk radio and Fox News to reinforce the message with the base. Media theorist Marshall McLuhan once predicted technology would create a global village. Instead, we’ve all gone back to our campfires. Mr. McCain doesn’t have to fan the flames. Allies in the new media will.

4. Be crisp and commanding. Mr. McCain’s widely hailed success at a forum a evangelical leader Rick Warren’s church this summer was in delivering clear answers with authority. His performance in the first debate was highlighted by his deep grasp of facts on international affairs.

Mr. McCain’s hopes rest on capturing the support of undecided voters in swing states. They are moved less by partisan attacks and more by confidence in a leader who will make their lives better. In recent days, Mr. McCain has cast himself as the cheerful warrior and steady commander. Former McCain aide John Weaver told Politico the public “wants to hear economic English,” not a candidate “speaking in angry Greek.”

5 . We are in crisis. Pound home that message, whether the subject is the economy or foreign affairs. Tie the two together, suggesting that another terrorist attack could further damage our economy, and ham-handed economic policies would leave us weaker against terrorists.

Mr. McCain must remind voters the next president won’t have time to study up before he acts. He should repeat the White House is not a place for on-the-job training — maybe even hold up the last two presidents as a bipartisan object lesson.